Cho S : = \(\frac{1}{5^2}+\frac{1}{9^2}+.....+\frac{1}{409^2}\) Chứng minh : S <\(\frac{1}{12}\)
Cho \(S=\frac{1}{5^2}+\frac{1}{9^2}+...+\frac{1}{409^2}.\)Chứng minh \(S<\frac{1}{12}\)
cho S = \(\frac{1}{5^2}+\frac{1}{9^2}+....+\frac{1}{409^2}\)chứng minh S <\(\frac{1}{12}\)
\(S=\frac{1}{5^2}+\frac{1}{9^2}+...+\frac{1}{409^2}\)
Chứng minh rằng S < \(\frac{1}{12}\)
Mong m.n giải cặn kẽ hộ mình. cảm ơn m.n
\(S=\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{9^2}\)
Chứng minh S<4/5
\(C=\frac{1}{5^2}+\frac{1}{9^2}+...+\frac{1}{409^2}.\)CHỨNG MINH \(C<\frac{1}{11}\)
Cho S=\(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+.....+\frac{1}{9^2}\)
Chứng minh rằng: \(\frac{2}{5}< S< \frac{8}{9}\)
Chứng minh :
1,C=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}.C< \frac{3}{4}\)
2,D=\(\frac{1}{5^2}+\frac{1}{9^2}+...+\frac{1}{409^2}< \frac{1}{12}\)
3,E=\(\frac{5}{5.8.11}+\frac{5}{8.11.14}+...+\frac{5}{302.305.308}< \frac{1}{48}\)
